CHAPTER III 



THE AUTONOMY OF THE INDIVIDUAL ORGANS OF THE 

 PROTOPLASTS 



5. Nucleus and Trophoplast 



A review of our knowledge concerning the anatomy 

 of the nucleus can be regarded as superfluous in this con- 

 nection. This knowledge is to be looked upon at present 

 as an established achievement of science, the significance 

 of which for the theory of heredity can hardly be doubted 

 any longer. Flemming in the zoological, Strasburger and 

 Schmitz in the botanical field have broken the way, and 

 their observations have been verified and extended in the 

 main by numerous other investigators. 



It does not seem to be quite fully decided whether the 

 amitotic nuclei, which have originated through constriction 

 and scission, are of significance in questions of heredity, 

 or whether they occur in somatic cells only, and not on 

 the germ-tracks. In Chara the nuclei in the apical cells 

 divide, according to Johow's investigations, according to 

 the usual scheme of indirect nuclear division ; the smaller 

 cells of the grown plant, for example in the nodes, remain 

 forever uni-nucleate, while the larger ones become multi- 

 nucleate through constriction. This kind of nuclear form- 

 ation, however, is never followed by cell-division. 30 Ac- 

 cording to Zimmermann direct nuclear division in the 

 plant-world "is limited to only those cases in which the 

 nuclear division is not accompanied by cell-division." 31 

 ' 30 Johow, F. Die Zellkerne von Chara foetida, Bot. Zeit. 31: 

 729. 1881. 



31 Zimmermann A. Morphologic und Physiologic der Pflansen- 

 zelle. p. 34. 



